Re: libdrm_amdgpu being forked and merged into Mesa

On 2024-10-25 12:18, Bas Nieuwenhuizen wrote:
> On Fri, Oct 25, 2024 at 11:21 AM Michel Dänzer <[email protected] <mailto:[email protected]>> wrote:
> 
>     On 2024-10-24 17:08, Marek Olšák wrote:
>     > We don't need to share the same VMID between ROCm and Mesa. We don't
>     > need to share the same driver FD between ROCm and Mesa either. It will
>     > be like having 2 different processes, and that should always work.
> 
>     Per https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31756#note_2626236 <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31756#note_2626236>, does anything prevent the application from passing the same DRM file description (doesn't need to be the same *descriptor*) to separate drivers? (Not sure it can even pass a DRM fd to ROCm, surely can e.g. to radeonsi & AMDVLK though)
> 
> 
> In RADV the app has no way to pass in a drm fd, there is only a way to query the major/minor from the fd (https://registry.khronos.org/vulkan/specs/1.3-extensions/html/chap55.html#VK_EXT_physical_device_drm <https://registry.khronos.org/vulkan/specs/1.3-extensions/html/chap55.html#VK_EXT_physical_device_drm>).

Hmm. So Wayland compositors which use Vulkan have to share BOs from Vulkan into their DRM file description for KMS via dma-buf?


How about ROCm, no way to pass in / retrieve a DRM file descriptor there either?


> (not to mention that it would mean that any users would need to use libdrm_amdgpu. Given that the most likely combination of GBM with shared fd/handle stuff is kernel modesetting and nobody uses libdrm_amdgpu with that, having a shared libdrm_amdgpu would not help there)

Not sure what you mean here, Wayland compositors use radeonsi with KMS.


-- 
Earthling Michel Dänzer       \        GNOME / Xwayland / Mesa developer
https://redhat.com             \               Libre software enthusiast